1. Field of the Invention
This invention relates to a fuel metering control system for an internal combustion engine.
2. Description of the Prior Art
The application of adaptive control theory to internal combustion engines in recent years has led to the development of technologies for adaptively controlling the actual quantity of fuel drawn into the engine cylinders to the desired fuel quantity, as taught, for example, by Japanese Laid-Open Patent Application No. Hei 1(1989)-110,853.
The present assignee's Japanese Patent Application No. Hei 6(1994)-66,594 (Japanese Laid-Open Patent Application No. Hei 7(1995)-247,886) (filed in the United States on Mar. 9, 1995 under the Ser. No. 08/401,430) also teaches fuel metering control in an internal combustion engine using adaptive control.
The system includes an adaptive controller which receives controller (system) parameters estimated/identified by an adaptation mechanism and forms a feedback compensator so as to bring a detected value to a desired value.
Since, however, the adaptive controller has a high response or convergency, it is preferable to discriminate whether the system operates stably and if not, to take any countermeasures to cope therewith. In the prior art system, there is no way for the discrimination to be made, except for waiting for the completion of the control.